Furnace cycle control



H. s. GANO 1,795,945

FURNACE CYCLE CONTROL Filed Nv. 50, 1926 5 Sheets-Sheet l March 10,1931.

A@ v mm INVENTOR f l q ATTORNEY 1n n Hor/670 5 Gana.

WITNEssEs; M7 ffm/w March 10, 1931. H. s GAN@ 1,795,945

FURNAOE CYCLE CONTROL I Filed Nov. 30, 1926 3 Sheets-Sheet 2 Q y@/Var/a/J 5 6000. f/m/' y* ATTORNEY I 5 sheets-sheet 3 Filed Nov,

LME

INVENTOR /Vdr/a/v 60H0- ATTO'RNEY WITNESSES:

yf/227@ *Y Patented Mar. 19, 1931 HABLAN S. GANO, OF MANSFIELD, OI-10,ASSIGNOR TO VESINGI-IOUSE ELECTRIC & MANUFACTURING COMPANY, ACORPORATION OF PENNSYLVANIA FUR-NACE CYCLE CONTROL Application filedNovember' 30, v1926. Serial No. 151,694.

My invention relates to furnace cycle control systems and particularlyto electrical control systems for rotary furnaces.

e An object of my invention is to provide an eiiicient cycle controlsystem for a furnace.

Another object of my invention is to provide an automatic controlsystem' for an intermittently operating rotary furnace.

Another object of my'invention is to provide electric means forchronometrically controlling the operation of a conveyer and of Va heath-tray dumping mechanism in a furnace. n

Another object of my invention is to pro- Y vide means vfor preventingsimultaneous operation of a conveyer and of a tilting mechanism. y

Another objectzoff my invention is to provide an automatically-actuatedmechanism for operating the charging door of a furnace.

Another object of my invention is vto provide a control system for aplural-hearth-tray rotary furnace, in which means operatively associatedwith the rotary hearth cle-energizes a hearth turning motor, which, inturn, cnergizes a 'tray-tilting motor, re-energizes the hearth-turningmotor and then cle-energizes its own circuit, this cycle beingcontinuted indefinitely. Y

Another object of my invention is to provide manual control means for afurnace that shall operate independently of the automatic control.

` Other objects of my invention will be apparent from the disclosure.

" In practisingmy inventionin accordance with thel present embodiment, lprovide separate electric motors for driving theconveyer and thehearth-tray dumping mechanism, respectively. Since these motors areintended to operate alternately, interlociing means are provided toprevent both motors operating at the ysame time.

Chronometric means is provided Vfor controlling the operation of thesemotors. Such means is started byv means controlled by the conveyer. Thechronometric means periodically and alternately causes the energizationof the conveyer-driving motor and of the tilting motor. Thedeenergization of the conrchamberl 15 therein. y are yprovided forsupporting the furnace.

Vey-er motor and of the tilting motor iscaused by means controlled bythe conveyer and the tilting mechanism, respectively. The chron-rometric means is self-stopping.

Pneumatic means is provided for opening the charging door. Such means isautomatically governed by means controlled by thel conveyer. i i

Manually operable means are provided for controlling the operation ofthe conveyer, the tilting mechanism and the charging door, independentlyof the automatic control means.

ln the drawings,

Figure 1 is a view, in vertical section, of a furnace to which mycontrol system is applied. y

2 is a view, in vertical section, of onehalf of the furnace, showing thechargingdoor mechanism, V'

Fig. 3 is adiagram of the wiring of the control system, Y

F ig. 4L is a detail diagrammatic view of a modification of the. timingdrum, and

`F ig. 5 is a vieW, in'vertical section and on an enlarged scale, of adoor-actuating means.

Referring to the drawing for a more de- V tailed description of myinvention, a furnace 19, shown in Figs. 1 and 2, comprises an outercylindrical casing 12, an inner cylindrical casing 13 and an annularrefractory heat and electric-insulating` lining 14 within the casings,the lining 14 having an annular Suitable supports 16 Suitable heatingmeans is provided and, in the present embodiment of my invention,- suchheating means comprises electric heating elements 18 positioned in thechamber 15 and secured to the chamber walls. rllhese heating elementsareconnected to` a source of energy (not shown). i

Any annularpassage or run-way 20 is providedin the bottom of thefurnace,the top thereof communicating with the annular ehamberl.v Anannular conveyor 22 comprises a refractory insulating. portion 28 and ametallic bottom portion 24 and is of such dimensions Vas to permit ofrotation in thel i annular passage 20. The bottom portion 24' isprovided with a plurality of pairs of spaced "itegral depending lugs orfiange members 25, wheels 27 beingv suitably mounted between the ings ofeach pair. rEhese wheels run on a circular traclr 28, thus providing ameans for rotatably supporting the conveyer 22. Suitable concentric sandseals 29 are provided to prever o loss by reason of convection currentsof air through the spaces between the walls of runway and the conveyor22.

Means are provided for driving the conveyer to cause it to rotate and,in the present embodiment, such means comprises a circular rach 8O thatmay be integral with the bottom portion 2e and is adapted to mesh with abevel gear 8l that is keyed on one end of a shaft 82, which is rotatablymounted on a support it. bevel gear is lreyed to the other end of theshaft 82 and engages a bevel gear 85 lreyed on the lower end of a shaft36 that extends vertic ily through the central portion of the furnaceand is rotatably mounted in bearings 37 and 88.

The shaft 86 is held in place, at its upper end, by any suitable means,uch as a collar 39. A bevel gear wheel d() is rigidly secured to theupper end of the shaft and engages a bevel gear pinion el that isrigidly secured to a shaft 4:2 of a speed-reducing device comprising aworm gear in a casing 43 and a worm actuated by an electric motor ed.TheV motor may be designated the conveyor-driving motor or thehearth-motor.

A plurality of hearth supports e5 are rigidly mounted at equal intervalson the top of the refractory insulating portion 28 of the conveyor 22. Amaterial-receiving hearth tray e7 is pivotally secured, at its outerend, to each hearth support normally in the position shown by the fulllines (Figs. The hearth tra-ys e7 are open at their outer ends for apurpose hereinafter to be made clear. rIhe inner ends of trays e7 extendbeyond the hearth support e5 to permit engagement with means forperiodically effecting the discharge of material from the hearth tray.

Such means, in the present embodiment of my invention, consists of atilting mechanism comprising a vertical shaft slidably positioned in apassageway 5l and having a projection 52 that extends under the innerofr a hearth tray when the tray is opposite a discharge outlet 54 andabove a quench tanlr 55. A connecting rod 56 operatively connects theshaft 50 with a gear Wheel rlhe gear wheel 58 is operatively connected,through a speed reducing device 59, to a prime mover 60, that may be anelectric niotor. The gear wheel 58 engages a gear wheel 62 that has asubstantially circular cam 63 associated therewith and driven therebyfor a 'purpose hereinafter to be made clear. The diameter of gear wheel62 is the same as that of gear wheel 58 so that they will operate at thesame number of revolutions per minute.

A sand seal 65 is provided to prevent heat loss upwardly through thepassageway 5l.

A charging door 67 is provided to normally closea charging opening 68,(see Fie. 2). rlhe charging opening is preferably positioned close tothe discharge outlet to permit the charging ofa hearth tray that hasbeen dumped there being one tray between tiem. This is to provide aspace between the outlet and the charging opening. A charging platformV69 may be provided, if desired, in order to facilitate the charging ofthe successive trays.

Means are provided to automatically operate the door 67. Such meanscomprises, in the present embodiment of my invention, a pneumaticallyoperated piston 70 (see Fig. 2) slidably tting in a cylinder 72 andconnected to one end of a piston rod 7 3 the other end of which isoperatively connected to the charging' door 67 by means of a cable 7 4;passing over a pulley 75. The Weight of the door 67 is such that it willnormally remain in its closed position andwill hold the piston 70 nearthe outer end of the cylinder 72.

One end of a pipe 77 is connected to the outer end of the cylinder 70and the other end thereof is connected to a chamber 78 of an air-valvehousing 79 (see Figs. 2 and 5). The housing 79 comprises the' centralchamber 78, and upper chamber 80, a lower chamber 8l and partitions 82and 83 that have valve seats 84 and 85, respectively, therein. f

A valvev 86 is maintained normally seated on the valve seat 85 by meansof a compression spring 87 located in the lower chamber 8l. The valve 86is secured to a valve rod 89. Spaced from the valve 86 and also securedto the valve rod 89 is a valve 90 that is adapted to seat on the valveseat 8st but is normally maintained in an open position by the spring87.

Normally, the lowerv chamber 8l is not in communication with the chamber78 While the chamber 8O is in communicationtherewith. The chamber isprovided with an outlet 91 that leads to the outside atmosphere. aninlet pipe 92 that is connected to a source of compressed air (notshown).

Means for automatically operating the valve rod 89 comprises a coremember 93 (see Figs. l and of an electromagnet that is rigidly securedto the valve rod 89, a coil 9e for energizing said core member and meansfor energizing the solenoid to be hereinafter described lt will 'beobvious from the foregoing, that, when the coil 9e is energized, thevalve rod 89 will be moved downwardly to seat the valve 90 and to unseatthe valve 86, and compressed air will iow from pipe 92 into cham- Thechamber 8l is provided with l ber 81'through the open seat 85 into thechamber 7 8 and the conduit 77` and into the outer end portion of thecylinder 72, and will operate the piston 70 against the weight of thedoor 67 and cause an .upward movement of the door.

lt will also be apparent from the drawing` and the foregoing descriptionthat, when the motor le is operating, the ccnveyer 22 will be driven tocause the hearth trays l? to progress through the chamber lt will alsobe apparent that, when the motor 60 is operated, the gear 58 will turnand the connecting rod 56, which is operatively secured thereto, willmove the shaft 50 iirst upwardly and then downwardly. ln movingupwardly, the shaft 50 will cause the projection 52`to engage Vthehearth tray i7 that is oppoy site to the discharge outlet 511, and thetray will thereby be tilted to cause the heattreated articles locatedthereon to tall through the discharge outlet 511 into the quench tanlr55 that is preferably lilled with oilto a level above the lower endvofthe discharge spout 541 yand thus provide an oil seal for the dischargeopening.

l provide control means for causing the periodical operation of thehearth conveyor,

of the tilting mechanism and of the chargingv door mechanism.Preferably, inthis type oi furnace, the conveyer is stationary while thetilting mechanism is operating, and vice versa. f 4

Fig. 3 shows one embodiment of my control system for periodicallyeilecting the a`oovenoted operations, in proper sequence. ln addition tothe motors ,All and and the door operating air cylinder 7 9, atiming-device driving motor 101 is connected to a contact drum 102through a variable-speed reduction device 103, the latter being shownschematically in the drawing, as it forms no. essential part of mypresent invention. rEhe device 103 may be of any suitable typepurchasable in the market and effective to vary the rotating speed ofthe drum 102 within relatively wide and adjustable limits. The'dru'm isshown in Fig. 3 in a developed condition; that is, all of the peripheralsurface oit the drum is shownras located in one plane, order toillustrate more clearl'I he shape ci a conduct- .ing plate 1011 securedto the surface thereof.

he plate 104 comprises tour integral portions 105, 106, 107, and 108,located in longitudinally spaced relation on the drum and all voisubstantially the same width. Portion 105 extends entirely around theperiphery oi" the drum, and is engaged by a fixed contact brush 109.Portion 106 is shor er in the peripheral direction so that itsperipheral extent is less than 3600 and is engaged by a brush 111.Portion 107 is relatively short peripherally and is engaged by a brush112, :he portion being so located perinherally, that it is engaged bythe brush very shortly after turning movement of the drum 102 has beenstarted. Portion 108 is also relatively short peripherally and is solocated as to be engaged by a brush 113 when the drum has been turnedthrough almost 360o. The laxial width of' the vwhich will be hereinafterdescribed indetail.

llfhen the switch 114 is in the position shown in Fig. 3, the controlsystem is connected for automatic operation, but it may be controlledmanually when the switch blades are thrown to the opposite position, aswill be hereinafter described more in detail.

The motor actuates intermittently a switch lever 113 that is pivotallymounted on a suitable lined member, (not shown), by

means oi spaced lugs 119 secured to a portion ot the rotating hearth, asis shown more parel'tl 11l'lld ti`t ticularry in nie lower y,eitianperdon o. lho. 1 of the drawing. The lever switch 113 c D has its orroller end maintained in yielding engagementwith a portion of the sandseal, hereinbet'ore described, by a'suitable spring. The illustration ofthis device in Tig. 3 ot the drawings is schematic only. The number oflugs 119 is equal to the number et heartn trays 17. The outer or contactend of the lever 118 normally engages a iixed contact member 121 but isdisengaged therefrom and caused to a second contact member 122 when theinner end of the lever is engaged by one of the lugs 119. The peripheralwidth of the respective lugs 119 is such that th lover 118 engagescontact member 1221er a very short time only, this time being that whenone tray has arrived in a position for unloading material locatedthereon and when, simultaneously, the second preceding tray is inposition for reloading. No mounting means lier .contact members 121 andV122 is shown in either ll 1 or Fig. y3 of the drawings, as any supportsuitable for the purpose may be employed.

'The motor 60 actuates a cam 63 having a single relatively narrowdepression in its peripheral surface, which surface is engaged by theinner or roller'ends ot two switch levers 123 and 124, which arepivotally mounted on suitable means, not shown, intermediate their ends.rllhe outer ends oi the respective contact levers cooperate withsubstantially lined contact members 125 and 126. rllhe lever 123normally in engagement with its cooperating contact member 125 anddisengagement therebetween is effected ronly when the roller end thereodrops into the single recess inthe cam surface. r"the lever 124 isnormally out et engagement with the contact member 126 llo 611101301'142. Reeys designe-ted by numerals 145 and 147 ae evelead lelays, thecells 01 v1 leb me Connected 111 che eSpeCmv-e motel' only when 111ecrcts etwee bhe circuit beekere and the ,I atm @011e en espeebve m01're, *ehe COTS U z thereby being 'tl-:mfesed the Seule errent Clli 44 ort1 e motor 60 soeve', so tfzuf'erses them and the 'elaye 147 N111 openthe lough 'the 180 and e i eaung eirf-md heeby e bhe motroie th 0, coi

1 ich 118, ceechczors 14,1

r- A v l, budgmg 141, conductor 146, endgeonduete i d be deszgneea ebeek #le other aum ry the peedle heel nd 117119111111211111- eufHy-eonbreled che, door Ugemtng The e ebenen paie 104, herein--reut,a.nd these ,1V1111e1 11er beeesebed befere described a eceied endrum 11A detail. 102, is eenneeed y-crcu; conductor on C11-enden Switch1431 'f iet@ 11" ",conduet0f148, i member of relay Contact and bdgngmemb' 147, conucte 146, bz 111g m mbel' o-relay relay 145 esse 145,onde/ter 144, @Rc1 Switch 143,150 supply dueto? 146,0011'f1ae idg-lngcircuit conducto-f 141. This eeut may be en over10ed relay n b1 A ydesgeeed, im? future leference, as a i3 44, eeudueor 1--1-Q 1 b1ae 11Tyreime Circuit.

tor 140,0011d1e" The timing-1110101" holding circuit eommembe1 121, C0201 pllees conducto? 142, pmt c- Conductor 157, blade 115, conde ter 1e011 15S e011 ef e1ay 158, condueor 165, bnf-.sb 111, breaker 134,0011111911 1 1v 5, back portions 106 and 105 of plete 104 and brush ""5member 139, eonduetos 15G and 109 to line 141 by theabove-describedreturn circuit which serves to maintain the coil of relay158 energized after the timing-motor starting circuit has been opened bydisengagement ofswitch 118l from contact inember 122. f l

` The tilting-motor starting circuit comprises conductor 157 connectedto supply-circuit conductor 142, conductor 156, baci; bridg' Thetilting-motor holding circuit com` prises conductor 157 connectedl tosupply-circuit conductor 142, part of conductor 156, back bridgingmember 188, conductor 166, coil 187, conductor 167, blade 116, conductor168, contact member 125, lever arm 123, associated with motor 60,conductors 171, 172, 151, and 149, blade 117, conductor 148, bridgingmember of relay 147, conductor 146, bridging member of coil 145,conductor 144 and through switch 148, to supply-circuit conductor 141.Theclosing of this circuit ensures energization of the tilting-motorindependently of the drum. l,

The periodic hearth-motor starting circuit comprises conductor 157connected to supplycircui't conductor 142, conductor 156, bridgingmember 139, conductor 155, coil 186, conductor 154, blade 115 andconductors 153 and 178 to brush 113, through portions 108 and 105 tobrush l109 and from thereback to the other supply-circuit conductor 141by, JShe above-described return circuit?7 s f Theautomaticallycontrolled chargingdoor operating circuitcomprises a partof conductor 157 connected to supply-circuit conductor 142, conductors186 and 185, a normally closed push-button switch 184, conductor 183,the coil of a relay 177, conductor 182,

Vcontact member 126, arm 124,'conductors 17,1,

172, 151 and 149,7blade 117, lconductor 148, bridging member of relay147, conductor 146, bridging member of relay 145, conductor 144 'andswitch- 148 to supply-circuit conductor 141.

AThe air-valvesolenoid energizing circuit comprises conductor 141,switch 148, conductor 144, bridging member of relay 145, conductor 146,bridging member of relay 147, conductor 148, blade 117 conductor 149,174 and 175, Contact members and the lower bridgingy member 176 of relay17 7 conductor 178, coil 94 of the air-fvalve device, conductors 179 and186 and, through a part of conductor 157, to supply-circuit'conductor142.

The air-valve-solenoid holding circuit comprises conductor 141, switch148, conductor 144, bridging member of relay 145, conductor 1,46,bridging member of relay 147, conduct@ 148,-blade 117 conductors 149,174 and 17 5 bridging member 181 of relay 17 7 conductor 182, coil ofrelayy l177, conductor 188,V pushbutton switchf184, conductors 185 yand186 anda part of Conductor 157 to supply-circuit conductor 142.

As has been noted hereinbefore, the system will operate automaticallyonly so long as switch 114 is inthe position shown in Fig. 8 of thedrawings.y When it is desired,vfor any reason,`toY control therespective devices manually, the switch blades are thrown to the leftandA cer-tain circuits may be energized as will be hereinaftersetforth.k

r1`hehearth-motor inching circuit comprises conductor 142, conductors157 and 156, bridg.

ing member189, conductor 155, coil oiAA relay 186, conductor 154, blade115, conductor 187l vto a normally open push-button switch 188,conductor 189, yconnected to one of the terminals of switch 188,.conductor 148, bridging member ofrelay 147 ,conductor 14.6, bridgingmember oi@A relay 145, conductor 144 and, through switch 143 tosupplyeeircuit conductor141. rlihis circuit is, of course,energized'only when switch 188 is held in its closed position, and ifswitch 114 is thrown to its eft-hand position.

rllhe tilting-motor Y prises conductor 142, conductor 157 apart inchingcircuit comof conductor 156, to the back bridging mem- Y ber 188,conductor 166, coil 187, conductor 167 to blade y116, conductor 191 toone-terminal of a normally/)open push-button switch 192, conductor 189ywhich is connected also to one terminal 4of switch 192, conductor 148,bridging member of relay 147, conductor 146, bridging member of relay145, conductor 144 and through switch 143, to conductor 141. Thiscircuit is energized only so long as switch 192 is held'closedby anoperator, andwhen the switch 114 has been thrown to its left-handposition. y

A manually-controllable chargingdoor energizing circuit comprisesconductor 141, switch 148, conductor-144, bridging member of relay 145,conductor 146, bridging member of relay 147 f,y conductor 148, blade 117con-k the positions shown in Fig. 8 of the drawings, and when the switch143 (which is shown in its open position but which will remain in eitherits open @rits closed position afterv having once been moved thereto anduntil again manually actuated to its other position) is closed, the mainhearth-motor starting circuit will be closed, thus energizing coil 136,whereby the breaker 134 is closed, the motor 44 is energized and willactuate the hearth as hereinbeore described.

The motor 44 will drive conveyer 22 until a tray filled with theheat-treated material arrives opposite to the discharge outlet, at whichtime the roller end of switch lever 118 will be engaged by a lug 119. asshown in Fig'. 1 of the drawings, and will be thrown to a positionopposite to that shown in Fig. 3. In this position of the switch lever,the timing- 'motor starting circuit will be closed, thus energizing coil158, closing the circuit through the timing motor by the bridgingmembers 161 and 162.

The timing motor being thus started will, in turn, cause the drum 102 torotate, and the rotation thereof will cause the engagement of brushes111 112 with the conducting surfaces 106 and 107, respectively` .shortlyafter the drum has begun to turn.

When the stationary contact member 111 enga ges the portion 106.v the timing-motor-holding-circuit will be closed. through the coil of relav158. to maintain the relay in its closed position independently of theinitial energizing circuit closed by the switch 118, as previouslydescribed.

Since the switch 118 is in a position opposite to that shown -in Fig. 3.the main hearthmotor starting circuit will be opened, relay 136 will bedeenergized and breaker 134 will be in its open position so that motor44 will be deenergized and the conveyer 22 will be stationary.

When stationary contact member 112 engages the portion 107 of theconducting surface 104, it is evident that the tilting-motor startingcircuit will be closed, and coil 137 will be energized, thus effectingclosing of circuit breaker 135, whereby tilting-motor 60 is energizedand causes an upward and then a downward movement of the tilting meansactuated by the motor 50, as has been Ahereinbefore described.

As the gear wheel 62 is in engagement Awith the gear wneel 58, it willbe rotated when the tilting' motor 60 is started. The cam 63, associatedwith the gear wheel, is adapted to normally maintain switch lever 123closed, that is, the outer contact end thereof engages the contactmember 125.

When switch 123 isclosed, it will close the tilting-motor holdingcircuit, thus maintaining a. circuit ythrough coil 137 so that breaker135, which controls the circuit of motor 60, will be maintained in itsclosed position after brush 112 is disengaged from the contact portion107, by the rotation of drum 102. When the gear wheels 58 and 62 haveVcompleted a one-halt` revolution, the recess in cam 63 will be engagedby the normally open switch 124 so that this switch can engage contactmember 126. Y A

The momentary engagement of switch lever 124 with the fixed contactmember 126 closes the automatically-controlled chargingdoor operatingcircuit and will thus energize solenoid 17 7, this action occurring whenthe hearth tray being dumped is in its highest raised position. Theenergization of the coil of relay 177 closes the air-valve-solenoidenergizing circuit, so that coil 94- is energized and core member 93 andthe valve stem and t-he valves operatively connected therewith are intheir lowered positions, unseating valve 86 and sea-ting valve 90, sothat compressed air may flow into chamber 78 from conduit 92 and intothe pipe 77 to operate the door-raising device. rEhe charging door 67 isthus raised to permit of charging the second tray ahead of the traybeing dumped. The door will be held open for apredetermined periodsutlicient for charging purposes. by the interlock member 181maintaining the energizing circuit of the coil of rei av 177.-

Vhen the switch 124 has its roller end in engagement with the recess incam 63. it will be closed, whereby the circuit through relay 177 isclosed. The air-valve coil 94 will, therefore, be maintained in anenergized condition until this circuit is interrupted'momentarily bypush-button switch 184. This deenergizes the coil of relay 177 and,therefore` interrupts the circuit through coil 94. The spring- 87,associated'with the valve stem, will again move the air valve into theposition shown, for instance. in Fig. 5 of the drawings. In thisposition. the supply of compressed air to cylinder 72 is shut oil| andpermits the door 67 to move piston 70, forcing the air from cylinder 72past valve 90 to the outside air, whereby door 67V will be closed. n i

When gear wheels 58 and 62 have made one complete revolution, and thehearth trav has been restored to its initial position.` switch 123 willagain engage the recess in cam 63 that it will be opened., thus openingthe tilting-motor holding circuit and deenergizing coil 137, thuscausing breaker 135 to open, whereby the motor 60 is deenergized and thetiltingmechanism is stopped. l

Shortly after this, the contact member 113 ot the timing-motor devicewill engage portion 108 of contact surfaces 104 because of the continuedrotation of drum 102. This engagement closes the periodic hearth-motorstarting circuit, and coil 136 will be energized, which will cause theclosing of breaker 134, so that hearth motor 44 is energized to restartthe conveyor 22. Rotation of the conveyer will eiiect the disengagementof switch 118-with lug 119, thus permitting switch 118 CII Y 158 toopen, wherebythe timing-motor energizing circuit is opened, and thetimingdevice drive motor is stopped.

Since the timing motor 101 may be a synchronous motor, it is obviousthat the timing motor and the drum switch 102 may operate as achronometric controlling device to time the opera-tion of the conveyor,the tilting mechanism and the charging-door mechanism. Since the motor101 is connectedto the drum through la variable-speed mechanism, thespeed of rotation of the drum 102 may be varied within relatively widelimits.

rlhe above described cycle of operations will be continued indefinitelyin the same sequence, so long as the supply circuitis energized and nochange in connections is made.

If it is desired to make repairs to the conveyor or to the tiltingmechanism, switch 114 is thrown to a position opposite to that shown inFig. 3, which permits the closing either of the hearth-motor inchiiigcircuit or the tilting-motor inching circuit by means of push-buttons188 or 192, respectively.

If push-button 188 is held closed by the operator, coil 136 isenergized, and breaker 134 will bev closed, thus causing theenergization and operation of motor 44 and conveycr 22. The push-buttonmay be held closed for a time necessary to bring the conveyor to thedesired position. ln like manner, the tilting mechanism may be caused tooperate by closing push-button switch 192 holding it closed for suchlength of time as will cause the members to move into the desiredpositions.

The normally open push-button vswitch 192 may be closed to cause theopening of charging door 67 by energizing the manually-controlledcharging-door operating circuit, and particularly of coil 94 When thispush-biitton is released it will again open the circuit, permitting thevalvesA lto again move to the position shown in 5er' they drawings, sothat the door 67 .is again closed, as was described above.

Bridging members 138 and 139 and their cooperating Contact membersprovide electric interlocking means for preventing simultaneousoperation of the tilting motor and of the hearth motor. that bridgingmember 139 is open when molt will be notedv tor 60 is operating, becauseofV the closing of the main contacts, as hereinbei'iore described,

while bridging member 138 will be disengaged from its Contact memberswhen the motor 44 isv energized by closing breaker 134. rlhevcircuitthrough coil 137 cr coil 136 being interrupted, will preventenergization of the corresponding motor.

A modii'ied iorm of lectric-connecting surfaces on the drum 102 to beoperated by motor 101 is shown in Fig. 4 of the drawings. The drum ishere provided with substantially'the same electric-conducting surta-ces105, 106, 107v and 108, as hereinbeiiore described to cooperate withstationary contact members 109,111, 112 and 113, and, in additionthereto, a contact `portion 201 and a cooperating brush or contactmember 202 are provided. The portion 201 is located in substantially thesame peripheral position as is portion 107. When this form ofelectric-conducting surface is used, conductor 182 is electricallyconnected to brush 202 in-v stead o to lever 124, so that, when brush202 engages lsuritace 201,-the following circuit 1T:

is established:

From conductor 141, through switch 143,

conductor 144, through the bridging members ofrelays 145 and 147connected by con- 'ductor 146, conductor 148, blade 117, conductor 149,partv of conductor 151, conductor 104, the electric-conducting surfaceson drum 102, portion 201, brush V.202, conductor 182, coil or relay 177,conductor 183, switch 184, ccnductors'185 and 186 and part of conductor157, to supply-circuit conductor 142. This energizes relay 177 so kthatthis relay will opcrate to energize coil 94 and cause door 67 to open.r1`he v:air-valve holding circuit for the above-described circuit willbe established automatically, as was hereinbefore set forth.

instead of employing an air valve 79 for operating the door, an electricmotor may be utilized, the energizing circuit of which may be controlledin the same manner and by t1 same circuits as have been alreadydescribed.

The energized condition of the hearthmoving motor circuit may beindicated by a visual signal 203 which is connected to contact member113 of the timing device and t0 supply-circuit conductor 142, and itwill therefore, be energized as long as the hearthmotor circuit isclosed.

Merely by vway of example and to indicate the times of Aoperations ofthe respective devices, it may be noted that the operating time oi" thehearth motor in moving the hearth overa peripheral distance equal to thedistance between the successive hearth trays is on the order. oit 20seconds, while thetime during which the hearth-moving motor isdeenergized may be varied from less than one minute to four or liveminutes. Ahearth tray is tilted during this time, and the secondpreceding hearth is reloaded, both of these operations usually inquiringless than the four oi' live minutes mentioned` above. HOW- evef, thistime is necessary oidei to insure that Jdie i" erial being` heattient-ed sliall remain in el s uiinece chamber a piepei lengtli tim beproperly tie-ated.

d, l may omit the tilting;v motor, case, tlie material will be iaked :emthe ,ys man: elly by an oiieiatoi". 10 Vani-.ous moe lifications may bemade in the systen'i and "evices embodying' my invention withoutdepeieing tiom the sjeiiit and scege tlieieot., and l cesiie that onlysuch limitatiene eliall lie placed theieen as are imposed by the pile?art ei aie set oitli in the appended claim.

l claim es my invention:

The combination with a fuinace, of a conveyei, an electiic motor fordriving seid conveyei, a plurality of hearth-trays pivotally mounted onsaid conveyer, mechanism ter tilting said lieaitli-tiays te successivelydiseliaige mateiial therefrom, a oi diiving said tilting mechanism, a pan" of noimally open ciicnit interrupters for controlling the operationof the cenveyerdiving metoi and the tilting meter, respectively,electiomagnets fer operating `said circuit inteiruptei's, a netay drumswitcli toi controlling the circuits of said electomagnets, asynchronous meter foi" clnonometiically driving said drum switch, aielay for contiolling said synclnenous meter, and means controlled bysaid eenveyei for initially energizing said' ielay., ln testimonywhereof, l have hereunto subscribed my name this 17 day of Novembei,

HABLAN S. GANO.

